<!doctype html>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<body>
<div id="main" style="height: 1000px; width: 1000px;"></div>
<script>
promise_test(async t => {
  // Wait for after the load event so that the navigation doesn't get converted
  // into a replace navigation.
  await new Promise(resolve => window.onload = () => t.step_timeout(resolve, 0));
  assert_equals(window.scrollY, 0);
  window.scrollTo(0, 100);
  assert_equals(window.scrollY, 100);
  navigation.onnavigate = e => e.intercept(
    { scroll: "after-transition",
      handler: async () => {
        if (e.navigationType == "push") {
          // Inserting this <div> should scroll *after* the scroll position
          // is saved, so that it doesn't break scroll restoration when going
          // back.
          let div = document.createElement("div");
          div.style = "height: 1000px; width: 1000px;";
          document.body.insertBefore(div, main);
        }
      }
    }
  );
  await navigation.navigate("?go").finished;
  // Ensure the layout changes and scroll position update from the first
  // navigation are processed before navigating back, otherwise the restored
  // scroll postion can be overwritten.
  await new Promise(resolve => requestAnimationFrame(resolve));
  await navigation.back().finished;
  assert_equals(window.scrollY, 100);
}, "scroll: state should be saved before intercept handlers run");
</script>
</body>
